sqlalchemy - 更新 Snowflake 中的混合和嵌套对象

Question

我有一个带有一个变体列 ( raw ) 的雪花表。
该表中的每一行都是复杂的(字典和数组)和嵌套的(多个层次结构)。
我想要做的是能够更新 具体 某个数组中的项目。
使用示例会更容易理解它，因此将其视为表中的一行:

{
  "id": "1234"
  "x_id": [
    {
      "y_id": "790437306684007491",
      "y_state": "some_state"
    }
  ],
  "comments": {
    "1": [
      {
        "comment_id": "bb288743-3b73-4423-b76b-f26b8c37f7d4",
        "comment_timestamp": "2021-02-10 14:53:25.667564",
        "comment_text": "Hey"
      },
      {
        "comment_id": "7378f332-93c4-4522-9f73-3b6a8a9425ce",
        "comment_text": "You",
        "comment_timestamp": "2021-02-10 14:54:21.337046"
      }
    ],
    "2": [
      {
        "comment_id": "9dd0cbb0-df80-4b0f-b399-9ee153161462",
        "comment_text": "Hello",
        "comment_timestamp": "2021-02-09 09:26:17.987386"
      },
      {
        "comment_id": "1a3bf1e8-82b5-4a9c-a959-a1da806ce7e3",
        "comment_text": "World",
        "comment_timestamp": "2021-02-09 09:28:32.144175"
      }
    ]
  }
}

而我想要的是更新评论文本 特定评论的 .
我知道我可以以编程方式更新整个 JSON 并使用 PARSE_JSON 更新整个对象，但这种方法还不够，因为可能有其他更新会覆盖其他评论，因此这种方法将失败(因为这些更新会相互覆盖)。
所以首先，我尝试了幼稚的方法(我知道这行不通，但我不得不尝试):

update table1
set raw['comments']['1'][0]["comment_text"] = 'please work'

毫不奇怪，我收到以下错误:

SQL compilation error: syntax error line 2 at position 7 unexpected '['.

接下来，我尝试了 OBJECT_INSERT这应该允许一种更新对象的方法，但由于嵌套键('1')而失败:

UPDATE table1
SET raw = OBJECT_INSERT(raw:comments:1, "comment_test", 'please work') 

有错误

SQL compilation error: syntax error line 1 at position 99 unexpected '1'.

(我也用 raw:comments:"1" 或 raw:comments:1[0] 或 raw['comments']['1'] 和其他一些方法尝试了这种方法的几种排列)
我还尝试重构对象，而不是将注释作为字典，而是将注释平铺到一个数组中，例如:

{
  "id": "1234"
  "x_id": [
    {
      "y_id": "790437306684007491",
      "y_state": "some_state"
    }
  ],
  "comments": [
      {
        "comment_id": "bb288743-3b73-4423-b76b-f26b8c37f7d4",
        "comment_timestamp": "2021-02-10 14:53:25.667564",
        "comment_text": "Hey"
        "comment_key": "1"
      },
      {
        "comment_id": "7378f332-93c4-4522-9f73-3b6a8a9425ce",
        "comment_text": "You",
        "comment_timestamp": "2021-02-10 14:54:21.337046"
        "comment_key": "1"
      }
      {
        "comment_id": "9dd0cbb0-df80-4b0f-b399-9ee153161462",
        "comment_text": "Hello",
        "comment_timestamp": "2021-02-09 09:26:17.987386",
        "comment_key": "2"
      },
      {
        "comment_id": "1a3bf1e8-82b5-4a9c-a959-a1da806ce7e3",
        "comment_text": "World",
        "comment_timestamp": "2021-02-09 09:28:32.144175",
        "comment_key": "2"
      }
    ]
}

但这并没有让我更接近解决方案。我找了一些 ARRAY_REPLACE替换数组中项目的函数，但看起来不存在这样的函数( all semi-structured related functions )
我也考虑过使用 JavaScript UDF 来做到这一点，但我没有找到任何可以实际更新行的 UDF 来源(它们都用于获取数据而不是更新它，与我所看到的相去甚远)。
有什么办法可以实现我想要的吗？
非常感谢!

Answer 1

您可以使用 JavaScript UDF 更新复杂的 JSON 结构。这是一个示例。请注意，您的两个 JSON 示例都有错误。我使用了第二个并修复了丢失的逗号。

-- Create a temp table with a sigle variant. By convention, I uses "v" as the name of any
-- column in a single-column table. You can change to "raw" in your code.
create or replace temp table foo(v variant);

-- Create a UDF that updates the exact key you want to update.
-- Unfortunately, JavaScript treats the object path as a constant so you can't make this 
-- a string that you pass in dynamically. There are ways around this possibly, but 
-- library restrictions would require a raw JavaScript parser function. Just update the
-- path you need in the UDF.
create or replace function update_json("v" variant, "newValue" string)
returns variant
language javascript
as
$$
   v.comments[0].comment_text = newValue;
   return v;
$$;

-- Insert the corrected JSON into the variant field
insert into foo select parse_json('{
    "id": "1234",
    "x_id": [{
        "y_id": "790437306684007491",
        "y_state": "some_state"
    }],
    "comments": [{
            "comment_id": "bb288743-3b73-4423-b76b-f26b8c37f7d4",
            "comment_timestamp": "2021-02-10 14:53:25.667564",
            "comment_text": "Hey",
            "comment_key": "1"
        },
        {
            "comment_id": "7378f332-93c4-4522-9f73-3b6a8a9425ce",
            "comment_text": "You",
            "comment_timestamp": "2021-02-10 14:54:21.337046",
            "comment_key": "1"
        },
        {
            "comment_id": "9dd0cbb0-df80-4b0f-b399-9ee153161462",
            "comment_text": "Hello",
            "comment_timestamp": "2021-02-09 09:26:17.987386",
            "comment_key": "2"
        },
        {
            "comment_id": "1a3bf1e8-82b5-4a9c-a959-a1da806ce7e3",
            "comment_text": "World",
            "comment_timestamp": "2021-02-09 09:28:32.144175",
            "comment_key": "2"
        }
    ]
}');

-- Show how the change works without updating the row
select update_json(v, 'please work') from foo;

-- Now update the row using the output. Note that this is updating the 
-- whole variant field, not a portion of it.
update foo set v = update_json(v, 'please work');

-- Show the updated key
select v:comments[0].comment_text::string from foo;

最后，如果您想修改一个必须先通过键查找所需内容的属性，您可以在 JavaScript 的循环中执行此操作。例如，如果它不是您需要的第 1 条评论，而是具有特定 UUID 或 comment_text 等的评论，您可以循环查找它并在循环的同一迭代中更新 comment_key。